Here we classified ZNF431 deficiency (OMIM618282), IL-6R deficiency (OMIM618944), IL6ST deficiency (OMIM618523, 619752), TGFBR deficiency (OMIM609192, 610168), and ERBIN deficiency (OMIM606944) as STAT3-related deficiencies. The gene discussed is ZNF431; the disease is hyperinsulinemic hypoglycemia, familial, 4.